I'm a semi-novice brewer (10 batches under my belt) and had a really bizarre SG with my latest batch. I was trying a Paulaner Hefeweizen clone recipe that called for 6 lbs. wheat DME to yield a 1.053 SG for a 5 gallon batch. My local brewstore didn't have much DME, so I improvised with 2 3.3 lb cans of Cooper's LME and 1 lb DME. I like to brew a 5.5 gallon batch so I can actually bottle about 5 gallons, so this combination should have resulted in a 1.052 SG (assuming an increase of 0.037 gallon-points/pound LME and 0.044 for DME). However, when I took a hydrometer reading prior to pitching, it read 1.040. I understand fluctuations of a few points here and there, but 25 % is a little unreasonable. The only cause I can think of is that the LME had a really low amount of fermentables in it.....

Has anyone had a similar problem????? (or another suggestion as to how this happened)

Yes, I have had this problem. My problem was that I had a 3 gallom boil and I topped off with water. I figured the mixing action from pouring water would be sufficient. My hydrometer read 1.028 when it should have been double that. My FG ten days later was 1.014. What I figured happened was that I did not mix the wort and the water enough. When I took a reading I gat a very watery sample and low reading.

BTW - The end beer tasted just fine and alcohol content felt normal for a 1.50 range beer.